Method of cladding metal surfaces



A118 9 1966 c. F. FUNK 3254,69

METHOD OF CLADDING METAL SURFACES Filed June 13, 1962 2 Sheets-Sheet 1 Aug. 9, 1966 c. F. FUNK 3,2649@ METHOD OF CLADDING METAL SURFACES Filed June 13, 1962 2 Sheets-Sheet 2` \Z'y.y.

70a INVENTOR @ma 55 FFZ//wf ATTORNEYS United States Patent O 3,264,696 METHOD F CLADDING METAL SURFACES Charles F. Funk, 11755 Sherbrook Drive, Baton Rouge, La. Filed June 13, 1962, Ser. No. 202,305 2 Claims. (Cl. 22-203) The present invention has'reference to a new and improved method of cladding the defective surface of worn parts wherein a thermit composition is reacted directly on the surface to be clad.

The thermit process for cladding metals is commonly carried out in a yCrucible wherein iron oxide and aluminum are reacted to form free iron in an exothermic reaction, when ignited, such as by magnesium. Necessarily, this exothermic reaction in a crucible is hazardous, in view of the excessively high temperature produced and the dangers incumbent in transferring the reduced molten metal to the surface being repaired. The pouring is a hazardous operation for molders, and is otherwise undesirable from the standpointV of the loss in temperature occurring by reason of the crucible being moved from a place of reaction to a subsequent position where the crucible is tapped and the metal is poured on the surface.

Accordingly, an important object of the present invention is to obviate the reaction of the thermit in a Crucible,

-the present invention contemplating a method of repairing a defective surface of the like wherein the thermit composition, 'generally in granular form, is initially placed directly on the defective surface to be clad. By virtue of this arrangement, the use of thermit becomes quite safe in that the metal is not poured in a molten state onto the metal surface.

Still further, this invention contemplates a new and improved method of repairing a worn metal surface of a type receptive to fusion with the reduced metal product of an exothermic thermit reaction, the thermit reaction and subsequent deposit of metal taking place in situ directly on the repaired surface.

While the cladding of metal with thermit is, in itself, known in the art, as evidenced by, e.g., the patent to Young, No. 2,309,288, issued in 1943, the instant invention contemplates the elimination of any preliminary reaction of the thermit in a Crucible remote from the surface to be repaired. Accordingly, the instant method of repairing defective surfaces enjoys the significant advantage of being relatively safe and free of hazards. Moreover, the instant invention readily lends itself to the repair of the rapidly worn surfaces Without the requirement for skilled molders.

According to this invention, .worn surface of a bar or other structure is first cleaned by conventional techniques, such as sand blasting, a chemical cleaning agent or the like. The structure is then placed in a sand mold form and the worn surface is placed upwardly in an exposed position. A core is temporarily positioned on the worn surface which configuration conforms to the desired finished configuration of the metal which is to be clad onto the worn surface, the sand being packed, as necessary, to conform to the configuration of the core. Preferably, spaced apart anchor studs are welded to the worn surface of the metal, these studs extending upwardly into the region formed by the core. These studs serve to fuse with the reduced free metal, plus whatever alloying composition is added to the thermit composition. While the use of studs welded to the worn surface is considered desirable, the same is not absolutely necessary, and successful results have been obtained without the use of studs.

The metal surface is then preheated; next, the thermit in the form of powder or granular composition is poured onto the mold from above the worn surface. The amount ICC of thermit required, of course, corresponds to the desired thickness of the cladding which is desired, and empirical methods have been found to be satisfactory. For example, a thickness ratio of 5:1 of thermit to the desired thickness of clad metal is a satisfactory relationship.

The thermit igniting mixture is then spread across the top surface of the unreacted thermit. In an exemplary arrangement, spaced apart piles of magnesium powder are positioned at regular intervals across the upper surface. Next, the magnesium powder is ignited, such as by fanning a blow torch iiame across this surface, thereby initiating the thermit reaction. The thermit reaction, well known in the art, causes a reduction of iron oxide to free iron, which is deposited onto the worn surface, this thickness corresponding to the configuration of the core which was originally placed adjacent the worn surface. The released iron (or alloyed iron) at this very high temperature fuses with the studs, if the same were used, and the clad metal is ultimately fused with the worn surface. The slag, which has risen to the top of the mold form, is conveniently removed by any suitable means such as ,a chipping hammer or the like. A structure is thereby clad in a notably superior manner and is capable of being reused until the surface is again Worn and the cladding is repeated to thereby prolong the useful life of the structure.

This invention also has application to cladding convex and concave surfaces; the method being modified to the extent risers and a core insert for the clad surface are provided.

The clad surface, particularly where the same is flat, is very smooth, minimum surface variation being provided by leveling the thermit composition prior to reacting the same.

The method according to this invention is particularly adapted for repairing the defective surfaces of parts which become rapidly worn due to environmental abuse. Typical of such structures are grizzly bars, which are used to convey and scalp large rocks, iron ore, coal and the like in conveyor equipment. This invention, however, is characterized by a high degree of flexibility, being adaptable for parts of both large and small sizes. A minimum of lost time for the equipment being repaired is occasioned by the fact any mold form is remarkably simple to construct, especially where at surfaces are to be clad. Moreover, the method is relatively safe to carry out, even with unskilled workmen, as well as being relatively inexpensive.

These and still further objects, advantages, and novel features of the present invention will become apparent in the specification and claims, taken in connection with the accompanying drawings.

In the drawings:

FIGURE l is a perspective view of a bar having a defective surface which is to be repaired according to the present invention;

FIGURE 2 shows, in an elevational section view, the bar positioned in a mold form together with the removable core positioned on the worn surface of the bar;

FIGURE 3 is a perspective view of the removable core in FIGURE 2;

FIGURE 4 is a View similar to FIGURE 2 showing studs welded to the worn surface; y

FIGURE 5 is a view of the subsequent step of placing the thermit powder onto the worn surface for subsequent reaction by the magnesium igniter;

FIGURE 6 is a perspective view, showing the ignition composition spaced on the top surface of the thermit prior to ignition;

FIGURE 7 is a view of the arrangement after the thermit reaction;

FIGURES is a perspective view of the repaired metal bar;

FIGURE 9 is an elevational section view similar to FIGURE 2 but showing a modified mold form land removable core; and

FIGURES l and 11 are elevational sectional kviews of an arrangement for [cladding convex and concave wom surfaces, respectively.

Referring now to the drawings, there is shown in FIG- URE 1 a grizzly lbar 10 of a T-shaped configuration, its upper surface 12 having become worn in the handling of ironore or the like. While the method is shown anddescribed as being carried 'out on the worn surface-of the grizzly bar, it will become apparent that this invention is capable of application to any worn surface,.to which clady metal is formed thereon to prolong the useful life of the worn part. The surface may be small or large, and as will thermit. The bar 10 is thenplaced in along metal box 14,1`

the surface 12 facing upwardly, the box 14 constituting the mold container for the bar10. Suitable angles 16 and.18 are positioned -along the bottom surface of the box 14 in opposed parallel relationship. Conveniently, the angles 16 l and 18 are tack Welded to the bottom end of the fbar 10. Molding sand 20with` its usual binder is packed into the metal box 14 so as to surround the bar 10, `except atitsn the dimensions of the clad metal to be formed,'i.e., the

configuration of the bar 10 after the same has been clad.

The sand 20. is tamped firmly about the `bar 10 andthe.

core 22, leaving a top recess of an inwardly inclined angular configuration 24.k Alternatively, the surface 24` of they top of Ithe sand mold may bein the form of vertical walls (FIGURE 9) so that there is provided a generally reci tangular recess along the length of the bar. In the latter modification, however, the core 22' is much thicker and no longer conforms to the `cladding thickness, but rather the mold thickness. The core 22 is'then Withdrawn, care be,- ing taken not to disturb the balance of the bar 10. Next,

the mold sandis firmly packed in the usual fashion and theV i mold is pre-heated with a conventional torch, heating the molding sand to about 200 F., to fix the binder therein.

Spaced .apart studs 26 may be welded to the ends of theV surface 12; the studs 26 will constitute an anchor for the clad metal as the same is fused on the surface 12 of the bar 10. Any dust or loose sand is then blown away from the worn surface 12 by an airhose or the like.

The surface is then preheated in the usual manner, to drive out moisture, and the like. Now, thermit 28,y of well-known composition, in the' form of a homogeneous powder, is poured into the recess 24 andstacked yto the desired height, the amount of thermit poured in the recess corresponding to the desired thickness of clad metal to be added Vto the worn surface 12. In `order to ensure a relatively level finish on the clad metal, with a minimum of rectly on the wo-rn surface 12, and is fused therewith andV with the studs 26 that were previously welded to the surface 12.

1943*. Accordingly, the instant method may be carried out with known thermit composition, which metal surface `is v receptive to fusion with the free metal product oftthe exothermic reaction. This Vmethod Works particularly well with a thermit 'composition exhibiting a highly uid slag, which slag lseparates and risesA quickly from the reduced metal.V The slag 32=Y rises to the top of thev clad metal surface 34.@ The entireV moldV is then :disassembled after the same sets, and the slag 32` islremoved with conventional techniques, suchfas a chipping hammer.

The top surface 34 of the repaired bar 10 is character-r Y ized;by asrnooth surface finish having a minimum of surface variation due to the fact the ,thermit was previously leveled in the mold. The barv10 is then ready for use i audits usefullife'has been prolonged, the bar 10 then being capable ofibeing repaired again, if necessary.

Referring now to FIGURES l0 and ll, there are shown arrangements foitfcladdingy convex v and, concave surfaces,

respectively, of: defective metal parts. f The part 10ain FIGURE 10 has` a worn or otherwise defective lconvex surface 12a,.the part being positioned in the mold box. 14 in a manner similar to that shown in FIGURE 2. In

this embodiment of the invention, a removable corer (not shown) with aconcavebottom surface was posi-v tioned against ythe convex surface 12 and the' sand packed to the top ofthe box 14.1 In thisgarrangernent, the .core` takes-the Vgeneralconiigurationoflrthati shown in FIG- URE 9 except for `the concave bottomsurface as de scribed.l Withzthe sand so packed, a core insert 36.is

positioned between the 7walls 24a,` and ithe mold recess above the surface 12a,` being spaced apart :from lthese `walls 24a toiform risers 38;l The concavefbottomsurface 40 ofthe insert 36finthis mode of carrying out the instant invention is left in place during the .thermit re` action, being positioned-a distance vfrom the surface 12a treated to withstand the high temperatures and is sup- -ported above `the mold box 1-4.by any suitable means.

sucht-as supporting barsr `42, joined thereto.

The thermit composition'28'inthis instance is then deposited into the ,riser spacers 38 filling this area and.

area adjacent the vsurface 12a. The piles of magnesium igniter are then spaced lalong the upper surfaces `of the 'thermit composition 28, :andpthese two rows of igniter are then started with a blow torch, initiating the thermit reaction. The dimensional relationship of the riser depth 38 is selected so that the vslag 32 formedin the' thermit reactioni'is` wholly within the riser zarea, the free metal `falling to -the surfacelZa wherethey same is fusedthereto, the clad surface 34a taking the .shape of 'the insert bottom surface Y40. After t-he metal lhas set, the mold is dismantled, the -slag chipped off, and the side extremities of thefclad surfaces are machined to complete Vthe con-1v Ifiguration of theclad surface.vl

In FIGUREy 11, the same processziis carried out except thatV the Vsurface 12a` is concave andthe corresponding bottom surface 40 of the kinsert 36 is convex. the process is thev same asethat described with reference to FIGURE 10.r

In`theV arrangements shown in FIGURES 10 and ll,

the insert 36 and the arrangement of the risers 38 renders the construction and operation somewhat more complex than theffla-t surface Vin l-8;\nevertheless, the use of a crucible and the ,hazards attendant therewith, is advan-` tageously eliminated.

From the foregoing description of the vvarious embodiments of this invention, Vit is evident that the objects of this invention, together with many practical advantages.: 4are successfully achieved.j While preferred embodiments of my invention have ,been described, numerous further Otherwise, v

modifications may be `made without departing yfrom the scope of this invention.

Therefore, it is to be understood that all matters herein set forth or shown in the accompanying dra'wings are to be interpreted in an illustrative and not in a limiting sense.

What is claimed is:

-1. A method of forming a built up surface layer of metal on a surface of a metal article, said surface being receptive to fusion, which comprises the steps of placing said article with said surface facing upwardly and in a generally horizontal position, forming a mold having upwardly-extending sides around an area of said surface, laying suicient thermit composition to form said built up layer on said surface within said sides, placing igniter material in contact with said thermit composition, igniting said igniter material, whereby the burning igniter material causes the ignition of said thermit composition and -a layer of molten metal is formed which fuses to said surface.

2. A method of forming a built up layer of metal on a surface of a metal article, said surface being receptive to fusion, lwhich comprises the steps of placing said article with said surface facing upwardly, forming a mold having upwardly-extending sides around an area of said surface defining a cavity over said surface, inserti-ng in said cavity mandrel having a lower `surface poised above said surface of said metal article, said mandrel bein-g smaller than cavity `and defining risers within said upwardly extending walls, placing sufcient thermit material i-n the space between said surfaces and within said risers to form said built up layer, placing igniter material on said thermit composition, igniting said igniter material whereby the burning igniter causes the ignition of said thermit com-position and a layer of molten metal is formed which fuses to said surface of said article.

References Cited by the Examiner UNITED STATES PATENTS 27,141 2/1860 McCain-mon 22-206 59,189 10/ 11866 Cornell 22-206 `620,071 2/ 1899 Heidelberg 22-r204 1,043,831 11/1912 Heinkel et al 22--206 1,090,296 3/ 1914 Goldschmidt. 1,531,472 3/1'925 Baker 22-57.2 1,607,118 '1l/'1926 Delachaux 22-204 1,619,139 3/ 1927 Laucks et al. 22-204 1,671,730 3/192'8 Lange. 2,002,223 2/ 1933 Earle. 2,220,210 11/ 1940 Chace 22-204 XR 2,235,199 3/ 1941 Chace 22-204 2,515,191 7/1950 Carpenter et al. 22-204 XR I. SPENCER OVERHOLZER, Primary Examiner.

WILLIAM I. STEPHENSON, M. V. BRINDISI,

Examiners.

V. K. RISING, Assistant Examiner. 

1. A METHOD OF FORMING A BUILT UP SURFACE LAYER OF METAL ON A SURFACE OF A METAL ARTICLE, SAID SURFACE BEING RECEPTIVE TO FUSION, WHICH COMPRISES THE STEPS OF PLACING SAID ARTICLE WITH SAID SURFACE FACING UPWARDLY AND IN A GENERALLY HORIZONTAL POSITION, FORMING A MOLD HAVING UPWARDLY-EXTENDING SIDES AROUND AN AREA OF SAID SURFACE, LAYING SUFFICIENT THERMIT COMPOSITION TO FORM SAID BUILT UP LAYER ON SAID SURFACE WITHIN SAID SIDES, PLACING IGNITER MATERIAL IN CONTACT WITH SAID THERMIT COMPOSITION IGNITING SAID IGNITER MATERIAL, WHEREBY THE BURNING IGNITER MATERIAL CAUSES THE IGNITION OF SAID THERMIT COMPOSITION AND A LAYER OF MOLTEN METAL IS FORMED WHICH FUSES TO SAID SURFACE. 